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| 2. |
- Al-Khafaji, Alia Hussain, et al.
(författare)
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Germination and stress tolerance of oats treated with pulsed electric field at different phases of seedling growth
- 2024
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Ingår i: Bioelectrochemistry. - 1567-5394 .- 1878-562X. ; 158
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Tidskriftsartikel (refereegranskat)abstract
- This study explores the impact of pulsed electric field (PEF) application on oat seedling growth and stress tolerance. PEF treatment (99 monopolar, rectangular pulses lasting 10 µs each, with a frequency of 13 Hz and a nominal electric field strength of 2250 V/cm) was applied at two growth stages: (i) when the seedlings had 0.2 cm roots emerging from the kernel, and (ii) when they had a 0.4 cm shoot emerging from the kernel. Post-treatment, the seedlings were hydroponically grown for 8 days. To induce stress, the hydroponic medium was augmented with PEG (15 %) to induce drought stress and NaCl (150 mM) to induce salinity stress. Results demonstrate that applying PEF improved the growth of the root and shoot of oat seedlings. This effect was more pronounced when applied to more developed seedlings. When PEF was applied during the later stage of germination, seedlings exposed to salinity stress showed enhanced shoot growth compared to the control. Under the studied conditions, the application of PEF had no impact on the growth of seedlings under drought stress.
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| 3. |
- Capelli, Filippo, et al.
(författare)
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Decontamination of food packages from SARS-COV-2 RNA with a cold plasma-assisted system
- 2021
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Ingår i: Applied Sciences (Switzerland). - : MDPI AG. - 2076-3417. ; 11:9
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Tidskriftsartikel (refereegranskat)abstract
- The accidental contamination of food and food packaging surfaces with SARS-CoV-2 is of increasing concern among scientists and consumers, particularly in relation to fresh foods that are consumed without further cooking. The use of chemical sanitizers is often not suitable for these kinds of commodities; therefore, a non-thermal sanitation technology could help to increase safety in relation to the food supply chain. Cold plasma has proven to be a promising strategy for virus inactivation. This research is aimed at evaluating the ability of a cold plasma sanitation system to inactivate SARS-CoV-2 RNA on packaged foods. Two different plastic materials were investigated and subjected to 5- and 10-min exposure to plasma after experimental inoculum of the RNA. In addition to viral degradation, possible changes in the performance of the materials were evaluated. Shelf-life of the foods, after exposure of the packages to plasma, was also investigated. Results showed that 10 min of exposure was sufficient to almost completely eliminate the viral RNA from package surfaces. The treatment did not produce any significant variation in packaging material performance or the shelf-life of the tested packaged products, indicating the potentiality of this treatment for the decontamination of packaged products.
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| 4. |
- Demir, Eda, et al.
(författare)
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Reversible electroporation caused by pulsed electric field – Opportunities and challenges for the food sector
- 2023
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Ingår i: Trends in Food Science and Technology. - 0924-2244. ; 139
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Forskningsöversikt (refereegranskat)abstract
- Background: The application of Pulsed Electric Field (PEF) to food may result in reversible or irreversible electroporation of cell membranes, depending on whether cell homeostasis is restored after resealing. Restoration of homeostasis upon reversible electroporation implies the recovery of the pre-pulse transmembrane potential and the restoration of cell metabolic functions. Enhanced membrane permeability caused by reversible electroporation would allow impregnation of cells with foreign molecules and/or stress-induced metabolic reactions. The impregnation of cells and the induction of stress in cells could open new opportunities for the application of PEF in the food industry. Scope and approach: Most of the published literature on the application of PEF in food systems focuses on the irreversible process, mainly targeting cold pasteurization or mass/heat transfer enhancement. This review focuses on the application of reversible electroporation to enhance metabolic production of secondary metabolites, to accelerate seed germination and fermentation, and as pre-treatment prior to freezing and drying. Finally, the challenges for industrial application of this technology are discussed. Key findings and conclusions: The application of reversible electroporation as a pre-treatment prior to unit operations in the food industry has the potential to improve the quality of the final product in terms of structure, nutritional value or increased productivity. However, its industrial application faces several challenges, related to difficulties in process optimization, scale-up and equipment design. Therefore, significant efforts are still required to apply reversible electroporation on an industrial scale in the future.
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| 5. |
- Demir, Eda, et al.
(författare)
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Technology Allowing Baby Spinach Leaves to Acquire Freezing Tolerance
- 2018
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Ingår i: Food and Bioprocess Technology. - : Springer Science and Business Media LLC. - 1935-5130 .- 1935-5149. ; 11:4, s. 809-817
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Tidskriftsartikel (refereegranskat)abstract
- This study focuses on improving the freezing tolerance of spinach leaves when applying vacuum impregnation (VI) and pulsed electric fields (PEF) as pre-treatments. Changing the cultivation conditions of the spinach plants was tested for improved freezing tolerance of the harvested leaves. Spinach plants were initially cultivated at 20 °C for 5 weeks and harvested at the beginning of week 6 before the cultivation conditions were changed to 5 °C. After exposing the plants to cold stress, leaves were harvested on day 1, 8, and 20. The leaves from different cultivation temperatures were treated with VI with 30% (w/v) trehalose solution and PEF prior freezing at − 22 °C in a blast freezer. After freezing and thawing, the viability of harvested spinach leaves was 50% for the plants cultivated at 20 °C for 5 weeks. When the cultivation conditions were changed, the viability of the harvested leaves increased to 82% on day 1, 89% on day 8, and without a significant further increase on day 20. During cold cultivation, sucrose accumulated in the leaves, which might have contributed to the increased survival. The influence of impregnating the accumulated sugars instead of changing the cultivation conditions on the survival of the leaves was tested. The viability of the leaves was 75%, which was higher than the survival of the control (50%). The results indicate that it is possible to increase leaf survival after freezing and thawing by applying VI and PEF in combination with either by changing the cultivation conditions of spinach plants or by externally impregnating additional sugars to the harvested leaves.
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| 6. |
- Galindo, Federico Gómez
(författare)
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Physiological and biochemical aspects of vegetable processing. A case study on carrots
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The aim of the present study was to enhance our understanding of vegetables as living organisms, interacting dynamically with the environment, and to explore the possible influence of metabolic changes on subsequent processing operations. Growing conditions, harvesting and handling in the packing house and storage conditions are key events leading to a defined “physiological status” of the vegetable that is going to be consumed as a fresh product or a processed product. Different events during the lifetime of vegetables are reviewed and analysed from the point of view of the physiological transformations taking place in each of them. Aspects of plant stress physiology were of particular interest. The physiological response to low-temperature stress, known as cold acclimation, was studied using carrots. The presence and accumulation of an antifreeze protein (AFP) in the carrot cell wall was used as a biological marker for the study of the induction of cold acclimation in carrot taproots. It was demonstrated that AFP gene expression was rapidly upregulated in response to low-temperature exposure. Furthermore, the induction of this gene was clearly affected by the temperature at which the taproots had been grown. The results also indicated that the development of cold acclimation in stored carrots, shown by the accumulation of AFP, was consistent with a high storage potential of the harvested taproots. The influence of cold acclimation on the mechanical strength of the harvested roots was studied. Tissue rigidity increased after 12 weeks of storage, at which time a higher accumulation of AFP was found. It was suggested that oxidative cross-linking between extensin proteins in the cell wall may be part of the mechanism behind the storage-induced firmness of carrots. The potential benefits of cold acclimation for the enhancement of quality upon freezing in the food industry are reviewed. The damaging action of a preceding blanching operation is discussed and the alternative of using mild blanching to minimize tissue damage was investigated. Isothermal calorimetry was used as a technique to quantify cell damage due to mild blanching of carrot slices. The results suggest that the mild blanching treatment, intended to inactivate the enzymes responsible for the development of off-flavours, may be accompanied by the inactivation of cell metabolism and hence, cell damage to about 70% of the cells in the carrot slices. Radiation in the far-infrared region was tested as a technological alternative to minimize cell damage. Radiation in the far-infrared region damaged cells to a depth of only 0.5 mm in the carrot slices, preserving cell integrity and most of the texture characteristics of the raw tissue. Basic scientific studies on the changes in vegetable cellular systems before harvest and after harvest and processing are necessary to provide the knowledge needed by food engineers on vegetables as biological materials. The use of this knowledge is of critical importance as a tool for process optimization in the food industry. The present study represents a contribution to this knowledge.
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| 7. |
- Galindo, Federico Gómez, et al.
(författare)
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Pulsed electric fields in combination with vacuum impregnation for improving freezing tolerance of vegetables
- 2017
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Ingår i: Handbook of Electroporation. - Cham : Springer International Publishing. - 9783319328850 - 9783319328867 ; 3, s. 2135-2151
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Bokkapitel (refereegranskat)abstract
- Freezing is a widely used method of preserving food products. Efforts are currently being directed towards improving the quality of sensitive tissues of plant foods such as leaves, after freezing and thawing. One of the methods under investigation is the combination of vacuum impregnation (VI) with cryoprotectants and the application of a pulsed electric field (PEF) to the plant tissue prior to freezing. In this chapter were identify mechanisms for the efficient introduction of a cryoprotectant molecule into the heterogeneous structure of leaf tissue and improve our understanding of the consequences of the introduction of this foreign molecule into the tissue regarding cell metabolism, freezing point, and ice propagation rate. To obtain precise information on the electroporation of internally located cells, a three-dimensional numerical model of the cross section of a leaf was developed. Validation of the models showed the importance of the wax layer and stomata for the successful electroporation of all cells in the tissue. VI, and the subsequent application of PEF, increased the metabolic activity of the tissue. The increase in metabolic activity after VI was accompanied by the accumulation of trehalose-6-phosphate in the cells. Leaves impregnated with trehalose, sucrose, glucose, and mannitol exhibited significantly lower ice propagation rates and higher freezing temperatures than untreated controls. Leaves subjected to PEF also showed higher freezing temperatures than untreated leaves; however, the ice propagation rate was not influenced by PEF.
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| 8. |
- Galindo, Federico Gómez
(författare)
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Responses of plant cells and tissues to pulsed electric field treatments
- 2017
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Ingår i: Handbook of Electroporation. - Cham : Springer International Publishing. - 9783319328850 - 9783319328867 ; 4, s. 2621-2635
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Bokkapitel (refereegranskat)abstract
- Cell membrane electroporation/permeabilization may be achieved without affecting cell viability through strict control of the electric pulse parameters. This process is referred to as reversible permeabilization. Even if the cells survive the electric field treatment, they are subjected to stress due to the opening of pores and the struggle of the cells to recover their normal functionality. Very little is known about what actually occurs in the cell and its membranes at the molecular level upon reversible electroporation, and the physiological responses to pulsed electric field (PEF)-induced stress are still largely unknown. This chapter explores the current state of the art on the influence of the complexity of plant tissues on electroporation. Focusing on reversible electroporation, metabolic responses of plant cells and tissues induced by PEF application are also reviewed. One of the first challenges when electroporating plant tissue is their heterogeneous structures where cells vary in shape, size, and cell wall structure. This heterogeneity influences the effect of different electric fields protocols aiming at permeabilizing all cells in the tissue. Once cells are reversibly permeabilized, physiological responses to PEF-induced stress include the production of reactive oxygen species, mobilization of stored energy, activation of stress-related genes, and the production of secondary metabolites. The application of reversible PEF has also been shown to barley seed germination as well as to increase the strength of the cell wall in potatoes and, in consequence, their textural properties. This chapter finishes by revising the effect of reversible PEF on protoplasts (plant cells where the cell walls have been removed) and, in consequence, on the regeneration of new plants. Overall, reports on reversible permeabilization of plant cells and tissues are not common in the literature; however, they have laid the foundation for a fascinating area of research and technological innovation.
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| 9. |
- Kanafusa, Sumiyo, et al.
(författare)
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Influence of pulsed electric field-assisted dehydration on the volatile compounds of basil leaves
- 2022
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Ingår i: Innovative Food Science and Emerging Technologies. - : Elsevier BV. - 1466-8564. ; 77
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Tidskriftsartikel (refereegranskat)abstract
- Pulsed electric field (PEF) was applied to basil leaves prior air drying at 40 °C. The parameters of the electric treatment were designed in such a way that (i) electroporated the tissue reversibly, provoking a permanent opening of the stomatal guard cells and (ii) electroporated the tissue irreversibly, damaging the cells. Treated leaves lost some volatile compounds due to both PEF treatments, probably related with the direct effect of permeabilization on the secretory cells of glandular trichomes. Upon drying, the irreversible permeabilization treatment showed the highest influence on the profile of volatiles in the dried leaves showing better retention of some terpenoids than the control. The performed statistical analysis allowed to select six compounds that can be used as markers both for the effect of pre-treatments prior dehydration and for the effects of dehydration itself on the volatile compounds of basil leaves.
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| 10. |
- Kanafusa, Sumiyo, et al.
(författare)
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The effect of nanosecond pulsed electric field on the production of metabolites from lactic acid bacteria in fermented watermelon juice
- 2021
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Ingår i: Innovative Food Science and Emerging Technologies. - : Elsevier BV. - 1466-8564. ; 72
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Tidskriftsartikel (refereegranskat)abstract
- Lactic acid fermentation offers a processing alternative for preservation of watermelon juice, which is sensitive to heat, oxygen, and light. In this study, 8.8 × 107 CFU/mL of Lactobacillus plantarum DSM 9843 in MRS broth was inoculated in 9.9 mL of sterilized watermelon juice. Nanosecond-pulsed electric field was applied during the log growth phase of the bacteria. An 19% increase in L-lactic acid, 6.8% increase in D-lactic acid and 15% increase in acetic acid were observed over control. The final pH was 3.8. These increased levels of metabolites were dependent on the applied voltages (L-lactic acid: 5.0 kV 700 pulses, D-lactic acid: 4.5 kV 700 pulses and acetic acid: 4.5 kV 1000 pulses). The nsPEF treatment did not affect the viability of the cells and sufficient numbers remained in the product after fermentation (1.6 × 109 CFU/mL in average). These results suggest that the metabolism of lactic acid bacteria was stimulated by the PEF treatment.
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